There are two filamentous wheat mosaic viruses transimitted by the plasmodiophoraceous fungus Polymyxa graminis :one is wheat spindle streak mosaic virus (WSSMV)first reported in Canada and the other is wheat yellow mosaic virus (WYMV) first reported in Japan .These viruses are very similar in particle morphology,biological and serological properties, but different in genomic sequences. The results of RT-PCR and single strand conformation polymorphism analysis (SSCP) indicated that the fungal transmitted filamentous wheat mosaic viral pathogen occurred in successive crops at different sites in China is wheat yellow mosaic virus. SSCP analysis with the fragments amplified using several primer sets all gave different patterns ,indicating the presence of sequence variations among eight isolates collected at different sites in China.